Electroluminescent iridium compounds with fluorinated phenylpyridines, phenylpyrimidines, and phenylquinolines and devices made with such compounds

ABSTRACT

The present invention is generally directed to electroluminescent Ir(III) compounds, the substituted 2-phenylpyridines, phenylpyrimidines, and phenylquinolines that are used to make the Ir(III) compounds, and devices that are made with the Ir(III) compounds.

RELATED APPLICATION

This application is a continuation-in-part application of U.S. patentapplication Ser. No. 09/879,014, filed on Jun. 12, 2001, now pending,which claims the benefit of U.S. provisional application serial No.60/215,362 filed on Jun. 30, 2000 and claims the benefit of U.S.provisional application serial No. 60/224,273 filed on Aug. 10, 2000.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to electroluminescent complexes of iridium(III)with fluorinated phenylpyridines, phenylpyrimidines, andphenylquinolines. It also relates to electronic devices in which theactive layer includes an electroluminescent Ir(II) complex.

2. Description of the Related Art

Organic electronic devices that emit light, such as light-emittingdiodes that make up displays, are present in many different kinds ofelectronic equipment. In all such devices, an organic active layer issandwiched between two electrical contact layers. At least one of theelectrical contact layers is light-transmitting so that light can passthrough the electrical contact layer. The organic active layer emitslight through the light-transmitting electrical contact layer uponapplication of electricity across the electrical contact layers.

It is well known to use organic electroluminescent compounds as theactive component in light-emitting diodes. Simple organic molecules suchas anthracene, thiadiazole derivatives, and coumarin derivatives areknown to show electroluminescence. Semiconductive conjugated polymershave also been used as electroluminescent components, as has beendisclosed in, for example, Friend et al., U.S. Pat. No. 5,247,190,Heeger et al., U.S. Pat. No. 5,408,109, and Nakano et al., PublishedEuropean Patent Application 443 861. Complexes of 8-hydroxyquinolatewith trivalent metal ions, particularly aluminum, have been extensivelyused as electroluminescent components, as has been disclosed in, forexample, Tang et al., U.S. Pat. No. 5,552,678.

Burrows and Thompson have reported that fac-tris(2-phenylpyridine)iridium can be used as the active component in organic light-emittingdevices. (Appl. Phys. Lett. 1999, 75, 4.) The performance is maximizedwhen the iridium compound is present in a host conductive material.Thompson has further reported devices in which the active layer ispoly(N-vinyl carbazole) doped withfac-tris[2-(4′,5′-difluorophenyl)pyridine-C′²,N]iridium(III). (PolymerPreprints 2000, 41(1), 770.)

However, there is a continuing need for electroluminescent compoundshaving improved efficiency.

SUMMARY OF THE INVENTION

The present invention is directed to an iridium compound (generallyreferred as “Ir(III) compounds”) having at least two 2-phenylpyridineligands in which there is at least one fluorine or fluorinated group onthe ligand. The iridium compound has the following First Formula:

IrL^(a)L^(b)L^(c) _(x)L′_(y)L″_(z)  (First Formula)

where:

x=0 or 1, y=0, 1 or 2, and z=0 or 1, with the proviso that:

x=0 or y+z=0 and

when y=2 then z=0;

L′=a bidentate ligand or a monodentate ligand, and is not aphenylpyridine, phenylpyrimidine, or phenylquinoline; with the provisothat:

when L′ is a monodentate ligand, y+z=2, and

when L′ is a bidentate ligand, z=0;

L″=a monodentate ligand, and is not a phenylpyridine, andphenylpyrimidine, or phenylquinoline; and

L^(a), L^(b) and L^(c) are alike or different from each other and eachof L^(a), L^(b) and L^(c) has structure (I) below:

wherein:

adjacent pairs of R₁ through R₄ and R₅ through R₈ can be joined to forma five- or six-membered ring,

at least one of R₁ through R₈ is selected from F, C_(n)F_(2n+1),

OC_(n)F_(2n+1), and OCF₂X, where n is an integer from 1 through 6 andX=H, Cl, or Br, and

A=C or N, provided that when A=N, there is no R₁.

In another embodiment, the present invention is directed to substituted2-phenylpyridine, phenylpyrimidine, and phenylquinoline precursorcompounds from which the above Ir(III) compounds are made. The precursorcompounds have a structure (II) or (III) below:

where A and R₁ through R₈ are as defined in structure (I) above,

and R₉ is H.

where:

at least one of R₁₀ through R₁₉ is selected from F, C_(n)F_(2n+1),OC_(n)F_(2n+1), and OCF₂X, where n=an integer between 1 and 6 and X isH, Cl, or Br, and R₂₀ is H.

It is understood that there is free rotation about the phenyl-pyridine,phenyl-pyrimidine and the phenyl-quinoline bonds. However, for thediscussion herein, the compounds will be described in terms of oneorientation.

In another embodiment, the present invention is directed to an organicelectronic device having at least one emitting layer comprising theabove Ir(III) compound, or combinations of the above Ir(III) compounds.

As used herein, the term “compound” is intended to mean an electricallyuncharged substance made up of molecules that further consist of atoms,wherein the atoms cannot be separated by physical means. The term“ligand” is intended to mean a molecule, ion, or atom that is attachedto the coordination sphere of a metallic ion. The term “complex”, whenused as a noun, is intended to mean a compound having at least onemetallic ion and at least one ligand. The term “group” is intended tomean a part of a compound, such a substituent in an organic compound ora ligand in a complex. The term “facial” is intended to mean one isomerof a complex, Ma₃b₃, having octahedral geometry, in which the three “a”groups are all adjacent, i.e. at the corners of one face of theoctahedron. The term “meridional” is intended to mean one isomer of acomplex, Ma₃b₃, having octahedral geometry, in which the three “a”groups occupy three positions such that two are trans to each other. Thephrase “adjacent to,” when used to refer to layers in a device, does notnecessarily mean that one layer is immediately next to another layer. Onthe other hand, the phrase “adjacent R groups,” is used to refer to Rgroups that are next to each other in a chemical formula (i.e., R groupsthat are on atoms joined by a bond). The term “photoactive” refers toany material that exhibits electroluminescence and/or photosensitivity.The term “(H+F)” is intended to mean all combinations of hydrogen andfluorine, including completely hydrogenated, partially fluorinated orperfluorinated substituents. By “emission maximum” is meant thewavelength, in nanometers, at which the maximum intensity ofelectroluminescence is obtained. Electroluminescence is generallymeasured in a diode structure, in which the material to be tested issandwiched between two electrical contact layers and a voltage isapplied. The light intensity and wavelength can be measured, forexample, by a photodiode and a spectrograph, respectively.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a light-emitting device (LED).

FIG. 2 is a schematic diagram of an LED testing apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The Ir(III) compounds of the invention have the First FormulaIr(III)L^(a)L^(b)L^(c) _(x)L′_(y) above.

The above Ir(III) compounds are frequently referred to as cyclometalatedcomplexes: Ir(III) compounds having the following Second Formula is alsofrequently referred to as a bis-cyclometalated complex:

IrL^(a)L^(b)L′_(y)L″_(z)  (Second Formula)

where:

y, z, L^(a), L^(b), L′, and L″ are as defined in the First Formulaabove.

Ir(III) compounds having the following Third Formula is also frequentlyreferred to as a tris-cyclometalated complex:

IrL^(a)L^(b)L^(c)  (Third Formula)

where:

L^(a), L^(b) and L^(c) are as defined in the First Formula describedabove.

The preferred cyclometalated complexes are neutral and non-ionic, andcan be sublimed intact. Thin films of these materials obtained viavacuum deposition exhibit good to excellent electroluminescentproperties. Introduction of fluorine substituents into the ligands onthe iridium atom increases both the stability and volatility of thecomplexes. As a result, vacuum deposition can be carried out at lowertemperatures and decomposition of the complexes can be avoided.Introduction of fluorine substituents into the ligands can often reducethe non-radiative decay rate and the self-quenching phenomenon in thesolid state. These reductions can lead to enhanced luminescenceefficiency. Variation of substituents with electron-donating andelectron-withdrawing properties allows for fine-tuning ofelectroluminescent properties of the compound and hence optimization ofthe brightness and efficiency in an electroluminescent device.

While not wishing to be bound by theory, it is believed that theemission from the iridium compounds is ligand-based, resulting frommetal-to-ligand charge transfer. Therefore, compounds that can exhibitelectroluminescence include those of compounds of the Second FormulaIrL^(a)L^(b)L′_(y)L″_(z) above, and the Third Formula IrL^(a)L^(b)L^(c)above, where all L^(a), L^(b), and L^(c) in the Third Formula arephenylpyridines, phenylpyrimidines, or phenylquinolines. The R₁ throughR₈ groups of structures (I) and (II), and the R₁₀ through R₁₉ groups ofstructure (III) above may be chosen from conventional substitutents fororganic compounds, such as alkyl, alkoxy, halogen, nitro, and cyanogroups, as well as fluoro, fluorinated alkyl and fluorinated alkoxygroups. The groups can be partially or fully fluorinated(perfluorinated). Preferred iridium compounds have all R₁ through R₈ andR₁₀ through R₁₉ substituents selected from fluoro, perfluorinated alkyl(C_(n)F_(2n+1)) and perfluorinated alkoxy groups (OC_(n)F_(2n+1)), wherethe perfluorinated alkyl and alkoxy groups have from 1 through 6 carbonatoms, or a group of the formula OCF₂X, where X is H, Cl, or Br.

It has been found that the electroluminescent properties of thecyclometalated iridium complexes are poorer when any one or more of theR₁ through R₈ and R₁₀ through R₁₉ groups is a nitro group. Therefore, itis preferred that none of the R₁ through R₈ and R₁₀ through R₁₉ groupsis a nitro group.

It has been found that the luminescence efficiency of the cyclometalatediridium complexes may be improved by using phenylpyridine,phenylpyrimidine, and phenylquinoline ligands in which some or all ofthe hydrogens have been replaced with deuterium.

The nitrogen-containing ring can be a pyridine ring, a pyrimidine or aquinoline. It is preferred that at least one fluorinated substituent ison the nitrogen-containing ring; most preferably CF₃.

Any conventional ligands known to transition metal coordinationchemistry is suitable as the L′ and L″ ligands. Examples of bidentateligands include compounds having two coordinating groups, such asethylenediamine and acetylacetonate, which may be substituted. Examplesof anionic bidentate ligands include beta-enolates, such asacetylacetonate; the anionic form of hydroxyquinolines, such as8-hydroxyquinoline, which may be substituted, in which the H from thehydroxy group has been extracted; aminocarboxylates; iminocarboxylates,such as pyridine carboxylate; salicylates; salicylaldimines, such as2-[(phenylimino)methyl]phenol; and phosphinoalkoxides, such as3-(diphenylphosphino)-1-propoxide. Examples of monodentate ligandsinclude chloride and nitrate ions; phosphines; isonitriles; carbonmonoxide; and mono-amines. It is preferred that the iridium complex beneutral and sublimable. If a single bidentate ligand is used, it shouldhave a net charge of minus one (−1). If two monodentate ligands areused, they should have a combined net charge of minus one (−1). Thebis-cyclometalated complexes can be useful in preparingtris-cyclometalated complexes where the ligands are not all the same.

In a preferred embodiment, the iridium compound has the Third FormulaIrL^(a)L^(b)L^(c) as described above.

In a more preferred embodiment, L^(a)=L^(b)=L^(c). These more preferredcompounds frequently exhibit a facial geometry, as determined by singlecrystal X-ray diffraction, in which the nitrogen atoms coordinated tothe iridium are trans with respect to carbon atoms coordinated to theiridium. These more preferred compounds have the following FourthFormula:

fac-Ir(L^(a))₃  (Fourth Formula)

where L^(a) has structure (I) above.

The compounds can also exhibit a meridional geometry in which two of thenitrogen atoms coordinated to the iridium are trans to each other. Thesecompounds have the following Fifth Formula:

mer-Ir(L^(a))₃  (Fifth Formula)

where L^(a) has structure (I) above.

Examples of compounds of the Fourth Formula and Fifth Formula above aregiven in Table 1 below:

TABLE 1 Compound A R₁ R₂ R₃ R₄ R₅ R₆ R₇ R₈ Formula 1-a C H H CF₃ H H H HH Fourth 1-b C H H CF₃ H H H F H Fourth 1-c C H H CF₃ H F H H H Fourth1-d C H H H H F H H H Fourth 1-e C H H CF₃ H H CF₃ H H Fourth 1-f C H HH H H CF₃ H H Fourth 1-g C H H H H H H F H Fourth 1-h C Cl H CF₃ H H H HH Fourth 1-i C H H CF₃ H H H OCH₃ H Fourth 1-j C H H CF₃ H H F H HFourth 1-k C H H NO₂ H H CF₃ H H Fourth 1-l C H H CF₃ H H H OCF₃ HFourth 1-m N — CF₃ H H H H F H Fourth 1-q C H H CF₃ H H OCH₃ H H Fourth1-r C H OCH₃ H H H H CF₃ H Fourth 1-s C H H H H F H F H Fourth and Fifth1-t C H H CF₃ H H F H F Fifth 1-u C H H CF₃ H F H F H Fifth 1-v C H HCF₃ H H H F H Fifth

Examples compounds of the Second Formula IrL^(a)L^(b)L′_(y)L″_(z) aboveinclude compounds 1-n, 1-o, 1 p, 1-w and 1-x, respectively havingstructure (IV), (V), (VI), (IX) and (X) below:

The iridium complexes of the Third Formula IrL^(a)L^(b)L^(c) above aregenerally prepared from the appropriate substituted 2-phenylpyridine,phenylpyrimidine, or phenylquinoline. The substituted 2-phenylpyridines,phenylpyrimidines, and phenylquinolines, as shown in Structure (II)above, are prepared, in good to excellent yield, using the Suzukicoupling of the substituted 2-chloropyridine, 2-chloropyrimidine or2-chloroquinoline with arylboronic acid as described in O. Lohse, P.Thevenin, E. Waldvogel Synlett, 1999, 45-48. This reaction isillustrated for the pyridine derivative, where X and Y representsubstituents, in Equation (1) below:

Examples of 2-phenylpyridine and 2-phenylpyrimidine compounds, havingstructure (II) above, are given in Table 2 below:

TABLE 2 Compound A R₁ R₂ R₃ R₄ R₅ R₆ R₇ R₈ R₉ 2-a C H H CF₃ H F H H H H2-b C H H CF₃ H H CF₃ H H H 2-c C H H NO₂ H H CF₃ H H H 2-d C H H CF₃ HH F H H H 2-e C H H CF₃ H H H CH₃O H H 2-f C Cl H CF₃ H H H H H H 2-g CH H H CH₃ H H F H H 2-h N — H H H H H F H H 2-i C H H CF₃ H H H CF₃O H H2-j N — CF₃ H H F H H H H 2-k C H H CF₃ H H H F H H 2-l C CF₃ H H H H HH H H 2-m C Cl H CF₃ H H H F H H 2-n C CF₃ H H H H H F H H 2-o C CF₃ H HH H H CH₃O H H 2-p C Cl H CF₃ H H H CH₃O H H 2-q N — CF₃ H H H H F H H2-r C Cl H CF₃ H H H H H F 2-s C H H CF₃ H H H H H H 2-t C Cl H H H F HH H H 2-v C H H CF₃ H H CH₃O H H H 2-w C H CH₃O H H H H CF₃ H H 2-x C HH H H H F F H H 2-y C H H CF₃ H H F H F H 2-z C H H CF₃ H F H F H H 2-aaC H H Br H H H Br H H

One example of a substituted 2-phenylquinoline compound, havingstructure (III) above, is compound 2-u, which has R₁₇ is CF₃ and R₁₀through R₁₆ and R₁₈ through R₂₀ are H.

The 2-phenylpyridines, pyrimidines, and quinolines thus prepared areused for the synthesis of the cyclometalated iridium complexes. Aconvenient one-step method has been developed employing commerciallyavailable iridium trichloride hydrate and silver trifluoroacetate. Thereactions are generally carried out with an excess of 2-phenylpyridine,pyrimidine, or quinoline, without a solvent, in the presence of 3equivalents of AgOCOCF₃. This reaction is illustrated for a2-phenylpyridine in Equation (2) below:

The tris-cyclometalated iridium complexes were isolated, purified, andfully characterized by elemental analysis, ¹H and ¹⁹F NMR spectral data,and, for compounds 1-b, 1-c, and 1-e, single crystal X-ray diffraction.In some cases, mixtures of isomers are obtained. Often the mixture canbe used without isolating the individual isomers.

The iridium complexes having the Second Formula IrL^(a)L^(b)L′_(y)L″_(z)above, may, in some cases, be isolated from the reaction mixture usingthe same synthetic procedures as preparing those having Third FormulaIrL^(a)L^(b)L^(c) above. The complexes can also be prepared by firstpreparing an intermediate iridium dimer having structure (VII) below:

wherein:

B=H, CH₃, or C₂H₅, and

L^(a), L^(b), L^(c), and L^(d) can be the same or different from eachother and each of L^(a), L^(b), L^(c), and L^(d) has structure (I)above.

The iridium dimers can generally be prepared by first reacting iridiumtrichloride hydrate with the 2-phenylpyridine, phenylpyrimidine orphenylquinoline, and adding NaOB.

One particularly useful iridium dimer is the hydroxo iridium dimer,having structure (VIII) below:

This intermediate can be used to prepare compound 1-p by the addition ofethyl acetoacetate.

Of particular interest, are complexes in which the emission has amaximum in the red region of the visible spectrum, from 570 to 625 nmfor red-orange, and from 625 to 700 nm for red. It has been found thatthe emission maxima of complexes of the Second and Third Formulae areshifted to the red when L has structure (XI) below, derived from aphenyl-quinoline compound having structure (III) above, or when L hasstructure (XII) below, derived from a phenyl-isoquinoline compound:

where:

at least one of R₁₀ through R₁₉ is selected from F, C_(n)F_(2n+1),OC_(n)F_(2n+1), and OCF₂X, where n is an integer from 1 through 6 and Xis H, Cl, or Br;

where:

at least one of R₂₁ through R₃₀ is selected from F,

C_(n)F_(2n+1), OC_(n)F_(2n+1), and OCF₂X, where n is an integer from 1through 6 and X is H, Cl, or Br.

It has also been found that the ligands of the invention can haveperfluoroalkyl and perfluoroalkoxy substituents with up to 12 carbonatoms.

In the Second Formula, the L′ and L″ ligands in the complex can beselected from any of those listed above, and are preferably chosen sothat the overall molecule is uncharged. Preferably, z is 0, and L′ is amonoanionic bidentate ligand, that is not a phenylpyridine,phenyhlpyrimidine, or phenylquinoline.

Although not preferred, complexes of the Second Formula also haveemission maxima that are shifted to the red when L is a phenylpyridineligand with structure (I) above, and L′ is a bidentate hydroxyquinolateligand.

Examples of compounds of the Second Formula, where L^(a) is the same asL^(b), L′ is a bidentate ligand, y is 1, and z is 0, and compounds ofthe Third Formula where L^(a), L^(b), and L^(c) are the same, are givenin Table 8 below. When L has structure (I) above, A is C. In this table,“acac” stands for 2,4-pentanedionate; “8hq” stands for8-hydroxyquinolinate; “Me-8hq” stands for 2-methyl-8-hydroxyquinolinate.

TABLE 8 Complex Ligand R Compound Formula Structure substituents L′ 8-aSecond I R₃ = CF₃ Me-8hq R₇ = F 8-b Second I R₃ = CF₃ 8hq R₇ = F 8-cSecond XI R₁₈ = CF₃ acac 8-d Second XII R₂₉ = CF₃ acac 8-e Second XIIR₂₈ = CF₃ acac 8-f Second XII R₂₉ = F acac 8-g Second XII R₂₇ = F acacR₂₉ = F 8-h Second XII R₂₇ = F acac R₂₉ = F R₃₀ = F 8-i Second XII R₂₈ =F acac R₂₉ = F R₃₀ = F 8-j Second XII R₂₈ = F acac R₃₀ = F 8-k SecondXII R₂₉ = C₈F₁₇ acac 8-l Third XII R₂₉ = CF₃ — 8-m Third XII R₂₈ = F —R₂₉ = F R₃₀ = F 8-n Third XII R₂₇ = F — R₂₉ = F R₃₀ = F 8-o Third XIIR₂₇ = F — R₂₉ = F 8-p Third XII R₂₈ = CF₃ — 8-q Third XII R₂₈ = F — R₃₀= F 8-r Second XII R₂₇ = F acac R₂₉ = F 8-s Second XII R₂₉ = OCF₃ acac

The complexes in Table 8 have emission maxima in the range of about 590to 650 nm.

Also of particular interest, are complexes in which the emission has amaximum in the blue region of the visible spectrum, from about 450 to500 nm. It has been found that the photoluminescence andelectroluminescence of the complexes are shifted to the blue when thecomplex has the Second Formula where L^(a) and L^(b) are phenyl-pyridineligands with an additional ligand selected from a phosphine, anisonitrile, and carbon monoxide. Suitable complexes have the SixthFormula below:

IrL^(a)L^(b)L′L″  (Sixth Formula)

where

L′ is selected from a phosphine, an isonitrile, and carbon monoxide;

L″ is selected from F, Cl, Br, and I

L^(a) and L^(b) are alike or different and each of L^(a) and L^(b) hasstructure (I) above, wherein:

R₁ through R₈ are independently selected from alkyl, alkoxy, halogen,nitro, cyano, fluoro, fluorinated alkyl and fluorinated alkoxy groups,and at least one of R₁ through R₈ is selected from F, C_(n)F_(2n+1),

OC_(n)F_(2n+1), and OCF₂X, where n is an integer from 1 through 6 and Xis H, Cl, or Br, and

A is C.

The phosphine ligands in the Sixth Formula preferably have the SeventhFormula below

P(Ar)₃  (Seventh Formula)

where Ar is an aromatic group, preferably a phenyl group, which may havealkyl or aryl substituents. Most preferably, the Ar group is a phenylgroup having at least one fluorine or fluorinated alkyl substituent.Examples of suitable phosphine ligands include (with the abbreviationprovided in brackets):

triphenylphosphine[PPh3]

tris[3,5-bis(trifluoromethyl)phenyl]phosphine [PtmPh3]

Some of the phosphine compounds are available commercially, or they canbe prepared using any of numerous well-known synthetic procedures, suchas alkylation or arylation reactions of PCl₃ or other P-electrophileswith organolithium or organomagnesium compounds.

The isonitrile ligands in the Sixth Formula, preferably have isonitrilesubstituents on aromatic groups. Examples of suitable isonitrile ligandsinclude (with the abbreviation provided in brackets):

2,6-dimethylphenyl isocyanide [NC-1]

3-trifluoromethylphenyl isocyanide [NC-2]

4-toluenesulfonylmethyl isocyanide [NC-3]

Some of the isonitrile compounds are available commercially. They alsocan be prepared using known procedures, such as the Hofmann reaction, inwhich the dichlorocarbene is generated from chloroform and a base in thepresence of a primary amine.

It is preferred that L″ in the Sixth Formula is chloride. It ispreferred that L^(a) is the same as L^(b).

Examples of compounds of the Sixth Formula where L^(a) is the same asL^(b) and L″ is chloride, are given in Table 9 below, where R₁ throughR₈ are as shown in structure (I) above.

TABLE 9 Comp. L′ R₁ R₂ R₃ R₄ R₅ R₆ R₇ R₈ 9-a NC-1 H CH₃ H H F H F H 9-bNC-1 H H CH₃ H F H F H 9-c NC-1 H H H H F H F H 9-d NC-1 H H H H H CF₃ HH 9-e NC-1 H CH₃ H H H CF₃ H H 9-f NC-1 H H CF₃ H H H F H 9-g NC-1 H HCF₃ H H CF₃ H H 9-h NC-2 H H H H H CF₃ H H 9-i NC-3 H H CF₃ H H H F H9-j PPh3 H H CF₃ H H H F H 9-k PtmPh3 H H CF₃ H H H F H 9-l CO H H CF₃ HH H F H NC-1 is 2,6-(CH₃)₂C₆H₃NC; NC-2 is 3-CF₃C₆H₄NC; NC-3 is4-CH₃C₆H₄SO₂CH₂NC; PPh₃ is P(C₆H₅)₃ PtmPh3 is (Ar_(f))₃P, where Ar_(f) =3,5-(CF₃)₂C₆H₃;

The complexes in Table 9 have emission maxima in the range of about 450to 550 nm.

Electronic Device

The present invention also relates to an electronic device comprising atleast one photoactive layer positioned between two electrical contactlayers, wherein the at least one layer of the device includes theiridium complex of the invention. Devices frequently have additionalhole transport and electron transport layers. A typical structure isshown in FIG. 1. The device 100 has an anode layer 110 and a cathodelayer 150. Adjacent to the anode is a layer 120 comprising holetransport material. Adjacent to the cathode is a layer 140 comprising anelectron transport material. Between the hole transport layer and theelectron transport layer is the photoactive layer 130. Layers 120, 130,and 140 are individually and collectively referred to as the activelayers.

Depending upon the application of the device 100, the photoactive layer130 can be a light-emitting layer that is activated by an appliedvoltage (such as in a light-emitting diode or light-emittingelectrochemical cell), a layer of material that responds to radiantenergy and generates a signal with or without an applied bias voltage(such as in a photodetector). Examples of photodetectors includephotoconductive cells, photoresistors, photoswitches, phototransistors,and phototubes, and photovoltaic cells, as these terms are describe inMarkus, John, Electronics and Nucleonics Dictionary, 470 and 476(McGraw-Hill, Inc. 1966).

The iridium compounds of the invention are particularly useful as thephotoactive material in layer 130, or as electron transport material inlayer 140. Preferably the iridium complexes of the invention are used asthe light-emitting material in diodes. It has been found that in theseapplications, the fluorinated compounds of the invention do not need tobe in a solid matrix diluent in order to be effective. A layer that isgreater than 20% by weight iridium compound, based on the total weightof the layer, up to 100% iridium compound, can be used as the emittinglayer. This is in contrast to the non-fluorinated iridium compound,tris(2-phenylpyridine) iridium (III), which was found to achieve maximumefficiency when present in an amount of only 6 to 8% by weight in theemitting layer. This was necessary to reduce the self-quenching effect.Additional materials can be present in the emitting layer with theiridium compound. For example, a fluorescent dye may be present to alterthe color of emission. A diluent may also be added. The diluent can be apolymeric material, such as poly(N-vinyl carbazole) and polysilane. Itcan also be a small molecule, such as 4,4′-N,N′-dicarbazole biphenyl ortertiary aromatic amines. When a diluent is used, the iridium compoundis generally present in a small amount, usually less than 20% by weight,preferably less than 10% by weight, based on the total weight of thelayer.

In some cases the iridium complexes may be present in more than oneisomeric form, or mixtures of different complexes may be present. Itwill be understood that in the above discussion of OLEDs, the term “theiridium compound” is intended to encompass mixtures of compounds and/orisomers.

To achieve a high efficiency LED, the HOMO (highest occupied molecularorbital) of the hole transport material should align with the workfunction of the anode, the LUMO (lowest unoccupied molecular orbital) ofthe electron transport material should align with the work function ofthe cathode. Chemical compatibility and sublimation temp of thematerials are also important considerations in selecting the electronand hole transport materials.

The other layers in the OLED can be made of any materials which areknown to be useful in such layers. The anode 110, is an electrode thatis particularly efficient for injecting positive charge carriers. It canbe made of, for example materials containing a metal, mixed metal,alloy, metal oxide or mixed-metal oxide, or it can be a conductingpolymer. Suitable metals include the Group 11 metals, the metals inGroups 4, 5, and 6, and the Group 8 through 10 transition metals. If theanode is to be light-transmitting, mixed-metal oxides of Groups 12, 13and 14 metals, such as indium-tin-oxide, are generally used. The IUPACnumbering system is used throughout, where the groups from the PeriodicTable are numbered from left to right as 1 through 18 (CRC Handbook ofChemistry and Physics, 81^(st) Edition, 2000). The anode 110 may alsocomprise an organic material such as polyaniline as described in“Flexible light-emitting diodes made from soluble conducting polymer,”Nature vol. 357, pp 477-479 (Jun. 11, 1992). At least one of the anodeand cathode should be at least partially transparent to allow thegenerated light to be observed.

Examples of hole transport materials for layer 120 have been summarizedfor example, in Kirk-Othmer Encyclopedia of Chemical Technology, FourthEdition, Vol. 18, p. 837-860, 1996, by Y. Wang. Both hole transportingmolecules and polymers can be used. Commonly used hole transportingmolecules are:N,N′-diphenyl-N,N′-bis(3-methylphenyl)-[1,1′-biphenyl]-4,4′-diamine(TPD), 1,1-bis[(di-4-tolylamino) phenyl]cyclohexane (TAPC),N,N′-bis(4-methylphenyl)-N,N′-bis(4-ethylphenyl)-[1,1′-(3,3′-dimethyl)biphenyl]-4,4′-diamine(ETPD), tetrakis-(3-methylphenyl)-N,N,N′,N′-2,5-phenylenediamine (PDA),a-phenyl-4-N,N-diphenylaminostyrene (TPS), p-(diethylamino)benzaldehydediphenylhydrazone (DEH), triphenylamine (TPA),bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylphenyl)methane (MPMP),1-phenyl-3-[p-(diethylamino)styryl]-5-[p-(diethylamino)phenyl]pyrazoline (PPR or DEASP), 1,2-trans-bis(9H-carbazol-9-yl)cyclobutane(DCZB), N,N,N′,N′-tetrakis(4-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine(TTB), and porphyrinic compounds, such as copper phthalocyanine.Commonly used hole transporting polymers are polyvinylcarbazole,(phenylmethyl)polysilane, and polyaniline. It is also possible to obtainhole transporting polymers by doping hole transporting molecules such asthose mentioned above into polymers such as polystyrene andpolycarbonate.

Examples of electron transport materials for layer 140 include metalchelated oxinoid compounds, such as tris(8-hydroxyquinolato)aluminum(Alq₃); phenanthroline-based compounds, such as2,9-dimethyl-4,7-diphenyl-1, 10-phenanthroline (DDPA) or 4,7-diphenyl-1,10-phenanthroline (DPA), and azole compounds such as2-(4-biphenylyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole (PBD) and3-(4-biphenylyl)-4-phenyl-5-(4-t-butylphenyl)-1,2,4-triazole (TAZ).Layer 140 can function both to facilitate electron transport, and alsoserve as a buffer layer or confinement layer to prevent quenching of theexciton at layer interfaces. Preferably, this layer promotes electronmobility and reduces exciton quenching.

The cathode 150, is an electrode that is particularly efficient forinjecting electrons or negative charge carriers. The cathode can be anymetal or nonmetal having a lower work function than the anode. Materialsfor the cathode can be selected from alkali metals of Group 1 (e.g., Li,Cs), the Group 2 (alkaline earth) metals, the Group 12 metals, includingthe rare earth elements and lanthanides, and the actinides. Materialssuch as aluminum, indium, calcium, barium, samarium and magnesium, aswell as combinations, can be used. Li-containing organometalliccompounds can also be deposited between the organic layer and thecathode layer to lower the operating voltage.

It is known to have other layers in organic electronic devices. Forexample, there can be a layer (not shown) between the conductive polymerlayer 120 and the active layer 130 to facilitate positive chargetransport and/or band-gap matching of the layers, or to function as aprotective layer. Similarly, there can be additional layers (not shown)between the active layer 130 and the cathode layer 150 to facilitatenegative charge transport and/or band-gap matching between the layers,or to function as a protective layer. Layers that are known in the artcan be used. In addition, any of the above-described layers can be madeof two or more layers. Alternatively, some or all of inorganic anodelayer 110, the conductive polymer layer 120, the active layer 130, andcathode layer 150, may be surface treated to increase charge carriertransport efficiency. The choice of materials for each of the componentlayers is preferably determined by balancing the goals of providing adevice with high device efficiency.

It is understood that each functional layer may be made up of more thanone layer.

The device can be prepared by sequentially vapor depositing theindividual layers on a suitable substrate. Substrates such as glass andpolymeric films can be used. Conventional vapor deposition techniquescan be used, such as thermal evaporation, chemical vapor deposition, andthe like. Alternatively, the organic layers can be coated from solutionsor dispersions in suitable solvents, using any conventional coatingtechnique. In general, the different layers will have the followingrange of thicknesses: anode 110, 500 to 5000 Å, preferably 1000 to 2000Å; hole transport layer 120, 50 to 1000 Å, preferably 200 to 800 Å;light-emitting layer 130, 10 to 1000 Å, preferably 100 to 800 Å;electron transport layer 140, 50 to 1000 Å, preferably 200 to 800 Å;cathode 150, 200 to 10000 Å, preferably 300 to 5000 Å. The location ofthe electron-hole recombination zone in the device, and thus theemission spectrum of the device, can be affected by the relativethickness of each layer. Thus the thickness of the electron-transportlayer should be chosen so that the electron-hole recombination zone isin the light-emitting layer. The desired ratio of layer thicknesses willdepend on the exact nature of the materials used.

It is understood that the efficiency of devices made with the iridiumcompounds of the invention, can be further improved by optimizing theother layers in the device. For example, more efficient cathodes such asCa, Ba or LiF can be used. Shaped substrates and novel hole transportmaterials that result in a reduction in operating voltage or increasequantum efficiency are also applicable. Additional layers can also beadded to tailor the energy levels of the various layers and facilitateelectroluminescence.

The iridium complexes of the invention often are phosphorescent andphotoluminescent and may be useful in applications other than OLEDs. Forexample, organometallic complexes of iridium have been used as oxygensensitive indicators, as phosphorescent indicators in bioassays, and ascatalysts. The bis cyclometalated complexes can be used to sythesizetris cyclometalated complexes where the third ligand is the same ordifferent.

EXAMPLES

The following examples illustrate certain features and advantages of thepresent invention. They are intended to be illustrative of theinvention, but not limiting. All percentages are by weight, unlessotherwise indicated.

Example 1

This example illustrates the preparation of the 2-phenylpyridines and2-phenylpyrimidines which are used to form the iridium compounds.

The general procedure used was described in O. Lohse, P. Thevenin, E.Waldvogel Synlett, 1999, 45-48. In a typical experiment, a mixture of200 mL of degassed water, 20 g of potassium carbonate, 150 mL of1,2-dimethoxyethane, 0.5 g of Pd(PPh₃)₄, 0.05 mol of a substituted2-chloropyridine (quinoline or pyrimidine) and 0.05 mol of a substitutedphenylboronic acid was refluxed (80-90° C.) for 16 to 30 h. Theresulting reaction mixture was diluted with 300 mL of water andextracted with CH₂Cl₂ (2×100 mL). The combined organic layers were driedover MgSO₄, and the solvent removed by vacuum. The liquid products werepurified by fractional vacuum distillation. The solid materials wererecrystallized from hexane. The typical purity of isolated materialswas >98%. The starting materials, yields, melting and boiling points ofthe new materials are given in Table 3. NMR data and analytical data aregiven in Table 4.

TABLE 3 Preparation of 2-Phenyl Pyridines, Phenylpyrimidines andPhenylquinolines Compound Yield in % B.p./mm Hg (m.p.) in ° C. 2-s 70 —2-a 72 — 2-b 48 — 2-u 75 (76-78) 2-c 41 (95-96) 2-d 38 (39-40) 2-e 5574.5/0.1 2-g 86 71-73/0.07 2-t 65 77-78/0.046 2-k 50 (38-40) 2-m 8072-73/0.01 2-f 22 52-33/0.12 2-v 63 95-96/13 2-w 72 2-x 35 61-62/0.0952-y 62 (68-70) 2-z 42 66-67/0.06 (58-60) 2-aa 60

TABLE 4 Properties of 2-Phenyl Pyridines, Phenylpyrimidines andPhenylquinolines Analysis %, found (calc.) Compound ¹H NMR ¹⁹F NMR or MS(M⁺) 2-s 7.48(3H), −62.68 C, 64.50 7.70(1H), (64.57) 7.83(1H), H, 3.497.90(2H), (3.59) 8.75(1H) N, 6.07 (6.28) 2-a 7.19(1H), −60.82 (3F, s),C, 59.56 7.30(1H), −116.96 (1F, m) (59.75) 7.43(1H), H, 3.19 7.98(2H),(2.90) 8.07(1H) N, 5.52 9.00(1H) (5.81) 2-b 7.58(1H), −62.75 (3F, s), C,53.68 7.66(1H), −63.10 (3F, s) (53.60) 7.88(1H), H, 2.61 8.03(1H),(2.40) 8.23(1H), N, 4.53 8.35(1H) (4.81) 8.99(1H) 2-u 7.55(1H), −62.89(s) C, 69.17 7.63(1H), (70.33) 7.75(2H), H, 3.79 7.89(2H), (3.66)8.28(2H), N, 4.88 8.38(1H), (5.12) 8.50(1H) 2-c 7.53(1H), -62.14 (s) C,53.83 (53.73) 7.64(1H), H, 2.89 7.90(1H), (2.61) 8.18(1H), N, 9.998.30(1H), (10.44) 8.53(1H), 9.43(1H) 2-d 7.06(1H), −62.78 (3F, s), C,59.73 7.48(1H), −112.61 (59.75) 7.81(3H), (1F, m) H, 2.86 8.01(1H),(2.90) 8.95(1H), N, 5.70 (5.81) 2-e 3.80(3H) −62.63 C, 61.66 6.93(2H),(s) (61.90) 7.68(1H), H, 3.95 7.85(1H), (4.04) 7.96(2H), N, 5.538.82(1H), (5.38) 2-g 2.70(3H) −114.03 C, 76.56 7.10(3H), (m) (77.00)7.48(1H), H, 5.12 7.60(1H), (5.30) 8.05(2H), N, 5.43 (7.50) 2-t7.10(2H), −62.73 C, 50.51 7.35(2H), (3F, s) (52.17) 7.96(1H), −113.67 H,1.97 8.78(1H), (1F, m) (2.17) N, 5.09 (5.07) 2-k 7.08(2H), −62.75 C,60.39 7.62(1H), (3F, s) (59.75), H, 3.38 7.90(3H), −111.49 (2.90),8.80(1H), (m) N, 5.53 (5.51) 2-m 7.10(2H), −62.63 C, 52.13 7.80(2H),(3F, s) (52.17) 8.00(1H), −111.24 H, 2.16 8.75(1H), (m) (2.17) N, 4.85(5.07) 2-f 7.55(3H), −62.57 (s) 257(M^(+,) 7.77(2H), C₁₂H₇F₃ClN⁺),8.06(1H), 222(M—Cl) 8.87(1H) 2-v 3.8(3H), −62.70 ppm C, 61.66 (61.37),6.95(1H), H, 3.98 (3.67), 7.30(1H), N, 5.53 (5.48) 7.50(1H), 7.58(1H),7.75(1H), 7.90(1H), 8.87(1H) 2-w 8.54(1H, d), −63.08(3F, s) 8.21(2H, d),7.70(2H, d), 7.24(1H, s), 6.82(1H, dd), 3.91 (3H, s) 2-x 6.9(2H, m),−109.70 (1F, m), 7.18(2H, m), −113.35 (1F, m). 7.68(2H, m), 7.95(1H, m),8.65(1H, m); 2-y 6.94(1H), −62.72 (3F, s), 7.62(2H), −109.11 (2F, m)7.82(1H), 8.03(1H), 8.96(1H); 2-z 6.85(1H), −62.80 (3F, s), 6.93(1H),−107.65 (1F, m), 7.80, 7.90, −112.45 (1F, m). 8.05(3H), 8.89(1H); 2-aa7.70(3H, m), 7.85(3H, m), 7.80, 7.90, 8.85(1H, m).

Example 2

This example illustrates the preparation of iridium compounds of theFourth Formula fac-Ir(L^(a))₃ above.

In a typical experiment, a mixture of IrCl₃.nH₂O (53-55% Ir), AgOCOCF₃(3.1 equivalents per Ir), 2-arylpyridine (excess), and (optionally) asmall amount of water was vigorously stirred under N₂ at 180-195° C.(oil bath) for 2 to 8 hours. The resulting mixture was thoroughlyextracted with CH₂Cl₂ until the extracts were colorless. The extractswere filtered through a silica column to produce a clear yellowsolution. Evaporation of this solution gave a residue which was treatedwith methanol to produce colored crystalline tris-cyclometalated Ircomplexes. The complexes were separated by filtration, washed withmethanol, dried under vacuum, and (optionally) purified bycrystallization, vacuum sublimation, or Soxhlet extraction. Yields:10-82%. All materials were characterized by NMR spectroscopic data andelemental analysis, and the results are given in Table 5 below.Single-crystal X-ray structures were obtained for three complexes of theseries.

Compound 1-b

A mixture of IrCl₃.nH₂O (54% Ir; 508 mg),2-(4-fluorophenyl)-5-trifluoromethylpyridine, compound kk (2.20 g),AgOCOCF₃ (1.01 g), and water (1 mL) was vigorously stirred under a flowof N₂ as the temperature was slowly (30 min) brought up to 185° C. (oilbath). After 2 hours at 185-190° C. the mixture solidified. The mixturewas cooled down to room temperature. The solids were extracted withdichloromethane until the extracts decolorized. The combineddichloromethane solutions were filtered through a short silica columnand evaporated. After methanol (50 mL) was added to the residue theflask was kept at −10° C. overnight. The yellow precipitate of thetris-cyclometalated complex, compound b, was separated, washed withmethanol, and dried under vacuum. Yield: 1.07 g (82%). X-Ray qualitycrystals of the complex were obtained by slowly cooling its warmsolution in 1,2-dichloroethane.

Compound 1-e

A mixture of IrCl₃.nH₂O (54% Ir; 504 mg),2-(3-trifluoromethylphenyl)-5-trifluoromethylpyridine, compound bb (1.60g), and AgOCOCF₃ (1.01 g) was vigorously stirred under a flow of N₂ asthe temperature was slowly (15 min) brought up to 192° C. (oil bath).After 6 hours at 190-195° C. the mixture solidified. The mixture wascooled down to room temperature. The solids were placed on a silicacolumn which was then washed with a large quantity of dichloromethane.The residue after evaporation of the filtrate was treated with methanolto produce yellow solid. The solid was collected and purified byextraction with dichloromethane in a 25-mL micro-Soxhlet extractor. Theyellow precipitate of the tris-cyclometalated complex, compound e, wasseparated, washed with methanol, and dried under vacuum. Yield: 0.59 g(39%). X-Ray quality crystals of the complex were obtained from hot1,2-dichloroethane.

Compound 1-d

A mixture of IrCl₃.nH₂O (54% Ir; 508 mg),2-(2-fluorophenyl)-5-trifluoromethylpyridine, compound aa (1.53 g), andAgOCOCF₃ (1.01 g) was vigorously stirred under a flow of N₂ at 190-195°C. (oil bath) for 6 h 15 min. The mixture was cooled down to roomtemperature and then extracted with hot 1,2-dichloroethane. The extractswere filtered through a short silica column and evaporated. Treatment ofthe residue with methanol (20 mL) resulted in precipitation of thedesired product, compound d, which was separated by filtration, washedwith methanol, and dried under vacuum. Yield: 0.63 g (49%). X-Rayquality crystals of the complex were obtained fromdichloromethane/methanol.

Compound 1-i

A mixture of IrCl₃.nH₂O (54% Ir; 503 mg),2-(4-trifluoromethoxyphenyl)-5-trifluoromethylpyridine, compound ee(2.00 g), and AgOCOCF₃ (1.10 g) was vigorously stirred under a flow ofN₂ at 190-195° C. (oil bath) for 2 h 45 min. The mixture was cooled downto room temperature and then extracted with dichloromethane. Theextracts were filtered through a short silica column and evaporated.Treatment of the residue with methanol (20 mL) resulted in precipitationof the desired product, compound i, which was separated by filtration,washed with methanol, and dried under vacuum. The yield was 0.86 g.Additionally, 0.27 g of the complex was obtained by evaporating themother liquor and adding petroleum ether to the residue. Overall yield:1.13 g (72%).

Compound 1-q

A mixture of IrCl₃.nH₂O (54% lr; 530 mg),2-(3-methoxyphenyl)-5-trifluoromethylpyridine (2.50 g), AgOCOCF₃ (1.12g), and water (1 mL) was vigorously stirred under a flow of N₂ as thetemperature was slowly (30 min) brought up to 185° C. (oil bath). After1 hour at 185° C. the mixture solidified. The mixture was cooled down toroom temperature. The solids were extracted with dichloromethane untilthe extracts decolorized. The combined dichloromethane solutions werefiltered through a short silica column and evaporated. The residue waswashed with hexanes and then recrystallized from1,2-dichloroethane-hexanes (twice). Yield: 0.30 g. ¹⁹F NMR (CD₂Cl₂, 20°C.), δ: −63 (s). ¹H NMR (CD₂Cl₂, 20° C.), δ: 8.1 (1H), 7.9 (1H), 7.8(1H), 7.4 (1H), 6.6 (2H), 4.8 (3H). X-Ray quality crystals of thecomplex (1,2-dichloroethane, hexane solvate) were obtained from1,2-dichloroethane-hexanes. This facial complex wasorange-photoluminescent.

Compounds 1-a, 1-c, 1-f through 1-h, 1-j through 1-m, and 1-r weresimilarly prepared. In the preparation of compound 1-j, a mixture ofisomers was obtained with the fluorine in either the R₆ or R₈ position.

TABLE 5 Analysis NMR Compound (calcd(found) (CD₂Cl₂, 25° C.) 1-a C:50.3(50.1) ¹H: 6.8(1H), 6.9(1H), 7.0(1H), 7.8 H: 2.5(2.7) (2H),7.95(1H), 8.1(1H) N: 4.9(4.9) ¹⁹F: −63.4 Cl: 0.0(0.2) 1-b C: 47.4(47.3)¹H: 6.4(1H), 6.75(1H), 7.7(1H), 7.8 H: 2.0(2.1) (1H), 7.95(1H), 8.05(1H)N: 4.6(4.4) ¹⁹F: −63.4(s); −109.5(ddd) 1-c C: 47.4(47.2) ¹H: 6.6(1H),6.7(1H), 6.9(1H), 7.8 H: 2.0(2.0) (1H), 8.0(1H), 8.6(1H) N: 4.6(4.5)¹⁹F: −63.5(s); −112.8(ddd) 1-d C: 55.9(56.1) ¹H: 6.6(2H), 6.8(1H),7.0(1H), 7.6 H: 3.0(3.2) (1H), 7.7(1H), 8.4(1H) N: 5.9(5.8) ¹⁹F:−115.0(ddd) 1-e C: 44.1(43.3) ¹H: 6.9(1H), 7.1(1H), 7.8(1H), 8.0 H:1.7(2.1) (2H), 8.2(1H) N: 3.9(3.6) ¹⁹F: −63.0(1F), −63.4(1F) 1-f C:50.4(50.5) ¹H: 6.9(1H), 7.1(2H), 7.6(1H), 7.8 H: 2.5(2.7) (1H), 7.9(1H),8.1(1H) N: 4.9(4.9) ¹⁹F: −62.4 1-g C: 55.9(56.3) 1H; 6.4(1H), 6.7(1H),7.0(1H), 7.6 H: 3.0(3.2) (1H), 7.7(2H), 7.9(1H) N: 5.9(6.0) ¹⁹F:−112.6(ddd) 1-h C: 51.0(45.2) ¹H: 6.8(1H), 6.95(1H), 7.05(1H), 7.7 H:2.1(2.3) (1H), 8.0(1H), 8.9(1H) N: 4.9(4.2) ¹⁹F: −63.3 1-i C: 49.4(49.3)¹H: 3.6(3H), 6.3(1H), 6.6(1H), 7.7 H: 2.9(2.8) (2H), 7.85(1H), 7.95(1H)N: 4.4(4.4) ¹⁹F: −63.2 1-j C: 47.4(47.4) ¹H: 6.7(m), 7.1(m), 7.5(m),7.6(m), H: 2.0(2.3) 7.7(m), 8.0(m), 8.2(m) N: 4.6(4.7) ¹⁹F: 8 sresonances(−63.0-−63.6) and 8 ddd resonances(−92.2-−125.5) 1-k C:43.5(44.0) ¹H: 6.9(1H), 7.15(1H), 8.1(1H), 8.3 H: 1.8(2.1) (1H),8.45(1H), 8.6(1H) N: 8.5(8.4) ¹⁹F: −62.9 1-l C: 42.2(42.1) ¹H: 6.5(1H),6.7(1H), 7.75(1H), 7.85 H: 16.(1.8) (1H), 8.0(1H), 8.1(1H) N: 3.8(3.7)¹⁹F: −58.1(1F), −63.4(1F)

Example 3

This example illustrates the preparation of iridium complexes of theSecond Formula IrL^(a)L^(b)L^(c) _(x)L′_(y)L″_(z) above,

Compound 1-n

A mixture of IrCl₃.nH₂O (54% Ir; 510 mg),2-(3-trifluoromethylphenyl)quinoline (1.80 g), and silvertrifluoroacetate (1.10 g) was vigorously stirred at 190-195° C. for 4hours. The resulting solid was chromatographed on silica withdichloromethane to produce a mixture of the dicyclometalated complex andthe unreacted ligand. The latter was removed from the mixture byextraction with warm hexanes. After the extracts became colorless thehexane-insoluble solid was collected and dried under vacuum. The yieldwas 0.29 g. ¹⁹F NMR: −63.5 (s, 6F), −76.5 (s, 3F). The structure of thiscomplex was established by a single crystal X ray diffraction study.

Compound 1-o

A mixture of IrCl₃.nH₂O (54% Ir; 500 mg),2-(2-fluorophenyl)-3-chloro-5-trifluoromethylpyridine (2.22 g), water(0.3 mL), and silver trifluoroacetate (1.00 g) was stirred at 190° C.for 1.5 hours. The solid product was chromatographed on silica withdichloromethane to produce 0.33 g of a 2:1 co-crystallized adduct of thedicyclometalated aqua trifluoroacetato complex, compound 1-p, and theunreacted ligand. ¹⁹F NMR: −63.0 (9F), −76.5 (3F), −87.7 (2F), −114.4 (1F). The co-crystallized phenylpyridine ligand was removed byrecrystallization from dichloromethane-hexanes. The structures of boththe adduct and the complex were established by a single crystal X-raydiffraction study.

Example 4

This example illustrates the preparation of an hydroxo iridium dimer,having structure (VIII) above.

A mixture of IrCl₃.nH₂O (54% Ir; 510 mg),2-(4-fluorophenyl)-5-trifluoromethylpyridine (725 mg), water (5 mL), and2-ethoxyethanol (20 mL) was vigorously stirred under reflux for 4.5hours. After a solution of NaOH (2.3 g) in water (5 mL) was added,followed by 20 mL of water, the mixture was stirred under reflux for 2hours. The mixture was cooled down to room temperature, diluted with 50mL of water, and filtered. The solid was vigorously stirred under refluxwith 30 mL of 1,2-dichloroethane and aqueous NaOH (2.2 g in 8 mL ofwater) for 6 hours. The organic solvent was evaporated from the mixtureto leave a suspension of an orange solid in the aqueous phase. Theorange solid was separated by filtration, thoroughly washed with water,and dried under vacuum to produce 0.94 g (95%) of the iridium hydroxodimer (spectroscopically pure). ¹H NMR (CD₂Cl₂): −1.0 (s, 1H, IrOH), 5.5(dd, 2H), 6.6 (dt, 2H), 7.7 (dd, 2H), 7.9 (dd, 2H), 8.0 (d, 2H), 9.1 (d,2H). ¹⁹F NMR (CD₂Cl₂): −62.5 (s, 3F), −109.0 (ddd, 1F).

Example 5

This example illustrates the preparation of bis-cyclometalated complexesfrom an iridium dimer.

Compound 1-p

A mixture of the iridium hydroxo dimer (100 mg) from Example 4, ethylacetoacetate (0.075 mL; 4-fold excess), and dichloromethane (4 mL) wasstirred at room temperature overnight. The solution was filtered througha short silica plug and evaporated to give an orange-yellow solid whichwas washed with hexanes and dried. The yield of the complex was 109 mg(94%). ¹H NMR (CD₂Cl₂): 1.1 (t, CH₃), 3.9 (dm, CH₂), 4.8 (s, CH₃COCH,5.9 (m), 6.7 (m), 7.7 (m), 8.0 (m), 8.8 (d). ¹⁹F NMR (CD₂Cl₂): −63.1 (s,3F), −63.2 (s, 3F), −109.1 (ddd, 1F), −109.5 (ddd). Analysis: Calcd: C,44.9; H, 2.6; N, 3.5. Found: C, 44.4; H, 2.6; N, 3.3.

Compound 1-w

A solution of hydroxo iridium dimer from Example 4 (0.20 g) in THF (6mL) was treated with 50 mg of trifluoroacetic acid, filtered through ashort silica plug, evaporated to ca. 0.5 mL, treated with hexanes (8mL), and left overnight. The yellow crystalline solid was separated,washed with hexanes, and dried under vacuum. Yield (1:1 THF solvate):0.24 g (96%). ¹⁹F NMR (CD₂Cl₂, 20° C.), δ: −63.2 (s, 3F), −76.4 (s, 3F),−107.3 (ddd, 1F). ¹H NMR (CD₂Cl₂, 20° C.), δ: 9.2 (br s, 1H), 8.2 (dd,1H), 8.1 (d, 1H), 7.7 (m, 1H), 6.7 (m, 1H), 5.8 (dd, 1H), 3.7 (m, 2H,THF), 1.8 (m, 2H, THF).

Compound 1-x

A mixture of the trifluoroacetate intermediate, compound 1-w (75 mg),and 2-(4-bromophenyl)-5-bromopyridine (130 mg) was stirred under N₂ at150-155° C. for 30 min. The resulting solid was cooled to roomtemperature and dissolved in CH₂Cl₂. The resulting solution was filteredthrough silica gel and evaporated. The residue was washed several timeswith warm hexanes and dried under vacuum to leave a yellow,yellow-photoluminescent solid. Yield: 74 mg (86%). ¹⁹F NMR (CD₂Cl₂, 20°C.), δ: −63.1 (s, 3F), −63.3 (s, 3F), −108.8 (ddd, 1F), −109.1 (ddd,1F). ¹H NMR (CD₂Cl₂, 20° C.), δ: 8.2 (s), 7.9 (m), 7.7 (m), 7.0 (d), 6.7(m), 6.2 (dd), 6.0 (dd). The complex was meridional, with the nitrogensof the fluorinated ligands being trans, as confirmed by X-ray analysis.

Example 6

This example illustrates the preparation of iridium compounds of theFifth Formula mer-Ir(L^(a))₃ above.

Compound 1-s

This complex was synthesized in a manner similar to compound 1-n.According to the NMR, TLC, and TGA data, the result was an approximately1:1 mixture of the facial and meridional isomers.

Compound 1-t

A mixture of IrCl₃.nH₂O (54% Ir; 0.40 g),2-(3,5-difluorophenyl)-5-trifluoromethylpyridine (1.40 g), AgOCOCF₃(0.81 g), and water (0.5 mL) was vigorously stirred under a flow of N₂as the temperature was slowly (30-40 min) brought up to 165° C. (oilbath). After 40 min at 165° C. the mixture solidified. The mixture wascooled down to room temperature. The solids were extracted withdichloromethane until the extracts decolorized. The combineddichloromethane solutions were filtered through a short silica columnand evaporated. The residue was thoroughly washed with hexanes and driedunder vacuum. Yield: 0.53 g (49%). ¹⁹F NMR (CD₂Cl₂, 20° C.), δ: −63.55(s, 3F), −63.57 (s, 3F), −63.67 (s, 3F), −89.1 (t, 1F), −100.6 (t, 1F),−102.8 (dd, 1F), −118.6 (ddd, 1F), −119.3 (ddd, 1F), −123.3 (ddd, 1F).¹H NMR (CD₂Cl₂, 20° C.), δ: 8.4 (s), 8.1 (m), 7.9 (m), 7.6 (s), 7.5 (m),6.6 (m), 6.4 (m). The complex was meridional, as was also confirmed byX-ray analysis.

Compound 1-u

This complex was prepared and isolated similarly to compound 1-q, thenpurified by crystallization from 1,2-dichloroethane-hexanes. The yieldof the purified product was 53%. The complex is mer, as follows from theNMR data. ¹⁹F NMR (CD₂Cl₂, 20° C.), δ: −63.48 (s, 3F), −63.52 (s, 6F),−105.5 (ddd, 1F), −105.9 (ddd, 1F), −106.1 (ddd, 1F), −107.4 (t, 1F),−107.9 (t, 1F), −109.3 (t, 1F). ¹H NMR (CD₂Cl₂, 20° C.), δ: 8.6 (m), 8.3(s), 8.2 (s), 8.1 (m), 7.9 (m), 7.6 (m), 6.6 (m), 6.4 (m), 6.0 (m), 5.8(m).

Compound 1-v

This mer-complex was prepared in a manner similar to compound 1-w, usingthe trifluoroacetate dicyclometalated intermediate, compound 1-x, and2-(4-fluorophenyl)-5-trifluoromethylpyridine. ¹⁹F NMR (CD₂Cl₂, 20° C.),δ: −63.30 (s, 3F), −63.34 (s, 3F), −63.37 (s, 3F), −108.9 (ddd, 1F),−109.0 (ddd, 1F), −109.7 (ddd, 1F). ¹H NMR (CD₂Cl₂, 20° C.), δ: 8.3-7.6(m), 6.7 (m), 6.6 (dd), 6.3 (dd), 6.0 (dd). This yellow-luminescentmerisional complex isomerised to the green luminescent facial isomer,compound 1-b, upon sublimation at 1 atm.

Example 7

This example illustrates the formation of OLEDs using the iridiumcomplexes of the invention.

Thin film OLED devices including a hole transport layer (HT layer),electroluminescent layer (EL layer) and at least one electron transportlayer (ET layer) were fabricated by the thermal evaporation technique.An Edward Auto 306 evaporator with oil diffusion pump was used. The basevacuum for all of the thin film deposition was in the range of 10⁻⁶torr. The deposition chamber was capable of depositing five differentfilms without the need to break up the vacuum.

An indium tin oxide (ITO) coated glass substrate was used, having an ITOlayer of about 1000-2000 Å. The substrate was first patterned by etchingaway the unwanted ITO area with 1 N HCl solution, to form a firstelectrode pattern. Polyimide tape was used as the mask. The patternedITO substrates were then cleaned ultrasonically in aqueous detergentsolution. The substrates were then rinsed with distilled water, followedby isopropanol, and then degreased in toluene vapor for ˜3 hours.

The cleaned, patterned ITO substrate was then loaded into the vacuumchamber and the chamber was pumped down to 10⁻⁶ torr. The substrate wasthen further cleaned using an oxygen plasma for about 5-10 minutes.After cleaning, multiple layers of thin films were then depositedsequentially onto the substrate by thermal evaporation. Finally,patterned metal electrodes of Al were deposited through a mask. Thethickness of the film was measured during deposition using a quartzcrystal monitor (Sycon STC-200). All film thickness reported in theExamples are nominal, calculated assuming the density of the materialdeposited to be one. The completed OLED device was then taken out of thevacuum chamber and characterized immediately without encapsulation.

A summary of the device layers and thicknesses is given in Table 6. Inall cases the anode was ITO as discussed above, and the cathode was Alhaving a thickness in the range of 700-760 Å. In some of the samples, atwo-layer electron transport layer was used. The layer indicated firstwas applied adjacent to the EL layer.

TABLE 6 Alq₃ = tris(8-hydroxyquinolato) aluminum DDPA =2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline Ir(ppy)₃ =fac-tris(2-phenylpyridine) iridium MPMP =bis[4-(N,N-diethylamino)-2-methylphenyl](4-methyl- phenyl)methane HTlayer EL layer ET layer Sample (Thickness, Å) (Thickness, Å) (Thickness,Å) Compar- MPMP (528) Ir(ppy)₃ (408) DDPA (106) + Alq₃ (320) ative  1MPMP (520) Compound 1-b DDPA (125) + Alq₃ (365) (499)  2 MPMP (541)Compound 1-b DDPA (407) (580)  3 MPMP (540) Compound 1-e DDPA (112) +Alq₃ (340) (499)  4 MPMP (525) Compound 1-k DDPA (106) Alq₃ (341) (406) 5 MPMP (570) Compound 1-i DDPA (107) + Alq₃ (339) (441)  6 MPMP (545)Compound 1-j DDPA (111) + Alq₃ (319) (462)  7 MPMP (643) Compound 1-gDDPA (112) + Alq₃ (361) (409)  8 MPMP (539) Compound 1-f DDPA (109) +Alq₃ (318) (430)  9 MPMP (547) Compound 1-a DDPA (105) + Alq₃ (300)(412) 10 MPMP (532) Compound 1-h DDPA (108) + Alq₃ (306) (457) 11 MPMP(603) Compound 1-d DDPA (111) + Alq₃ (303) (415) 12 MPMP (551) Compound1-c DDPA (106) + Alq₃ (313) (465) 13 MPMP (520) Compound 1-l DDPA (410)(405) 14 MPMP (504) Compound 1-b DDPA (393) (400) 15 MPMP (518) Compound1-b DDPA (418) (153) 16 MPMP (556) Compound 1-m DDPA (430) (416) 17 MPMP(520) Compound 1-n DDPA (420) (419) 18 MPMP (511) Compound 1-o DDPA(413) (412) 19 MPMP (527) Compound 1-p DDPA (412) (425) 20 MPMP (504)Compound 1-q DPA (407) (417) 21 MPMP (525) Compound 1-t DPA (416) (419)22 MPMP (520) Compound 1-u DPA (405) (421)

The OLED samples were characterized by measuring their (1)current-voltage (I-V) curves, (2) electroluminescence radiance versusvoltage, and (3) electroluminescence spectra versus voltage. Theapparatus used, 200, is shown in FIG. 2. The I-V curves of an OLEDsample, 220, were measured with a Keithley Source-Measurement Unit Model237, 280. The electroluminescence radiance (in the unit of Cd/m²) vs.voltage was measured with a Minolta LS-110 luminescence meter, 210,while the voltage was scanned using the Keithley SMU. Theelectroluminescence spectrum was obtained by collecting light using apair of lenses, 230, through an electronic shutter, 240, dispersedthrough a spectrograph, 250, and then measured with a diode arraydetector, 260. All three measurements were performed at the same timeand controlled by a computer, 270. The efficiency of the device atcertain voltage is determined by dividing the electroluminescenceradiance of the LED by the current density needed to run the device. Theunit is in Cd/A.

The results are given in Table 7 below:

TABLE 7 ElectroluminescentProperties of Iridium Compounds Efficiency atApproximate Peak peak Peak Peak Radiance, radiance, efficiency,Wavelengths, Sample Cd/m2 Cd/A Cd/A nm Comparative 540 0.39 0.48 522 at22 V  1 1400 3.4 11 525 at 21 V  2 1900 5.9 13 525 at 25 V  3 830 1.713.5 525 at 18 V  4 7.6 0.005 0.13 521 at 27 V  5 175 0.27 1.8 530, 563at 25 V  6 514 1.5 2.2 560 at 20 V  7 800 0.57 1.9 514 at 26 V  8 12000.61 2 517 at 28 V  9 400 1.1 4 545 at 18 V 10 190 2.3 3.3 575 at 16 V11 1150 1.2 3.8 506, 526 at 25 V 12 340 0.49 2.1 525 at 20 V 13 400 3 5520 at 21 V 14 1900 5 9 525 15 2500 6 11 525 16 100 0.17 0.2 560 at 27 V17 3.5 0.005 0.014 575 at 28 V 18 30 0.08 0.16 590 at 26 V 19 2000 6 8532 at 21 V 20 350 0.60 1.6 595 at 26 V 21 1200 5 545 at 22 V 22 80 1540 at 19 V

The peak efficiency is the best indication of the value of theelectroluminescent compound in a device. It gives a measure of how manyelectrons have to be input into a device in order to get a certainnumber of photons out (radiance). It is a fundamentally importantnumber, which reflects the intrinsic efficiency of the light-emittingmaterial. It is also important for practical applications, since higherefficiency means that fewer electrons are needed in order to achieve thesame radiance, which in turn means lower power consumption. Higherefficiency devices also tend to have longer lifetimes, since a higherproportion of injected electrons are converted to photons, instead ofgenerating heat or causing an undesirable chemical side reactions. Mostof the iridium complexes of the invention have much higher peakefficiencies than the parent factris(2-phenylpyridine) iridium complex.Those complexes with lower efficiencies may also find utility asphosphorescent or photoluminescent materials, or as catalysts, asdiscussed above.

Example 8

This example illustrates the preparation of the ligand parent compound,1-(2,4-difluoro-phenyl)-isoquinoline, having Formula XI.

2,4-difluorophenylboronic acid (Aldrich Chemical Co., 13.8 g, 87.4mmol), 1-chloroisoquinoline (Adrich Chemical Co., 13 g, 79.4 mmol),tetrakistriphenylphosphine palladium(0) (Aldrich, 3.00 g, 2.59 mmol),potassium carbonate (EM Science, 24.2 g, 175 mmol), water (300 mL), anddimethoxyethane (Aldrich, 300 mL) were allowed to stir at reflux for 20h under N₂, after which time the mixture was cooled to room temperatureand the organic and aqueous layers were separated. The aqueous layer wasextracted with 3×150 mL of diethyl ether, and the combined organicfractions were dried with sodium sulfate, filtered, and the filtrate wasevaporated to dryness. The crude material was chromatographed on asilica gel column, first by eluting the catalyst byproduct with 4:1hexanes/CH₂Cl₂, and finally the product was eluted with CH₂Cl₂/MeOH(9.5:0.5, product R_(f)=0.7). The pure product fractions were collectedand dried in vacuo, to afford 17.7 g (92% isolated yield) of a lightyellow solid, >95% pure NMR spectroscopy. 1H NMR (CDCl₃, 296 K, 300MHz): δ 8.61 (1H, d, J=5.7 Hz), 7.89 (1H, d, J=8.2 Hz), 7.67-7.85 (3H,m), 7.52-7.63 (2H, m), 6.95-7.12 (2H, m) ppm. ¹⁹F NMR (CDCl₃, 296K, 282MHz) δ −109.01 (1F, brs), −109.87 (1F, d, JF-F =8.5 Hz).

Example 9

This example illustrates the preparation of the bridged dichloro dimer,[IrCl{2-(2,4-difluoro-phenyl)-isoquinoline}₂]₂.

1-(2,4-difluoro-phenyl)-isoquinoline from Example 8 (1.00 g, 4.15 mmol),IrCl₃(H₂O)₃ (Strem Chemicals, 703 mg, 1.98 mmol), and 2-ethoxyethanol(Aldrich Chemical Co., 25 mL) were allowed to stir at reflux for 15 h,after which time the precipitate was isolated by filtration, washed withmethanol, and allowed to dry in vacuo, to afford 1.04 g (74%) of theproduct as red-orange solid, >95% pure by NMR spectroscopy. ¹H NMR(CD₂Cl₂, 296 K, 300 MHz): δ 8.85 (2H, d, J 6.4 Hz), 8.38 (2H, dd, J=8.8and 9.5 Hz), 7.82-7.97 (m, 4H), 7.67-7.7.8 (2H, m), 6.81 (2H, d, J=6.4Hz), 6.42 (2H, ddd, J=2.4, 3.3, and 11.4 Hz), 5.25 (2H, dd, J=2.4 and8.8 Hz) ppm. ¹⁹F NMR (CDCl₃, 296K, 282 MHz) δ −95.7(2F, d, J_(F-F)=12Hz), −108.03 (2F, d, J_(F-F)=12 Hz).

Example 10

This example illustrates the preparation of the bis-cyclometallatediridium complex, [Ir(acac){1-(2,4-difluoro-phenyl)-isoquinoline}₂],complex 8-r in Table 8.

[IrCl{1-(2,4-difluoro-phenyl)-isoquinoline}₂]₂ from Example 9 (300 mg,0.212 mmol), sodium acetylacetonate (Aldrich Chemical Co., 78 mg, 0.636mmol), and 2-ethoxyethanol (10 mL) were allowed to stir at 120° C. for0.5 h. The volatile components were then removed in vacua. The residuewas taken up in dichloromethane, and this solution was passed through apad of silica gel with dichloromethane as the eluting solvent. Theresulting red-orange filtrate was evaporated to dryness, and thensuspended in methanol. The precipitated product was isolated byfiltration and dried in vacuo. Isolated yield=230 mg (70%). ¹H NMR(CD₂Cl₂, 296 K, 300 MHz): δ 8.40 (2H, dd, I=8.8 and 9 Hz), 7.97 (2H, d,J=8.1 Hz), 7.78 (2H, ddd, J=0.7, 6.6, and 7.8 Hz), 7.70 (2H, dd, J=1.3and 8.4 Hz), 7.66 (2H, d, J=6.4 Hz), 6.44 (2H, ddd, J=2.4, 5.9, and 10.8ppm), 5.68 (2H, dd, J=2.4 and 8.5 Hz), 5.30 (1H, s), 1.78 (6H, s). ¹⁹FNMR (CDCl₃, 296K, 282 MHz) δ −96.15 (2F, d, J_(F-F)=11.3 Hz), −109.13(2F, d, J_(F-F)=11.3 Hz).

Compounds 8-a through 8-k, and compound 8-s in Table 8 were preparedusing a similar procedure.

Compounds 8-l through 8-q in Table 8 were prepared using the procedureof Example 2.

Example 11

Thin film OLED devices were fabricated using the procedure according toExample 7. A summary of the device layers and thicknesses is given inTable 10. In all cases the anode was ITO as discussed above, and thecathode was Al having a thickness in the range of 700-760 Å.

TABLE 10 MPMP =bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylphenyl)- methane DPA =4,7-diphenyl-1,10-phenanthroline HT layer EL layer ET layer Sample(Thickness, Å) (Thickness, Å) (Thickness, Å) 11-1  MPMP Compound 8-a DPA(572) (419) (400) 11-2  MPMP Compound 8-b DPA (512) (407) (394) 11-3 MPMP Compound 8-c DPA (548) (441) (408) 11-4  MPMP Compound 8-d DPA(508) (410) (408) 11-5  MPMP Compound 8-e DPA (560) (421) (407) 11-6 MPMP Compound 8-f DPA (526) (409) (405) 11-7  MPMP Compound 8-g DPA(890) (408) (402) 11-8  MPMP Compound 8-h DPA (514) (465) (403) 11-9 MPMP Compound 8-i DPA (564) (418) (413) 11-10 MPMP Compound 8-j DPA(564) (405) (407) 11-11 MPMP Compound 8-k DPA (522) (400) (408) 11-12MPMP Compound 8-l DPA (529) (421) (408) 11-13 MPMP Compound 8-m DPA(530) (411) (411) 11-14 MPMP Compound 8-o DPA (537) (412) (409) 11-15MPMP Compound 8-p DPA (509) (405) (405) 11-16 MPMP Compound 8-q DPA(512) (414) (402) 11-17 MPMP Compound 8-r DPA (529) (442) (412) 11-18MPMP Compound 8-s DPA 102961-31 (524) (407) (408)

The OLED samples were characterized as in Example 7, and the results aregiven in Table 12 below.

TABLE 11 Electroluminescent Properties of Iridium Compounds Peak PeakApproximate Peak Sample Radiance, Cd/m2 efficiency, Cd/A Wavelengths, nm11-1  45 0.13 628 at 22 V 11-2  32 0.12 >600  at 20 V 11-3  340 2.5 590at 24 11-4  350 1.7 625 at 22 V 11-5  300 1.5 >600  at 21 V 11-6  2001.1 605, 650 at 20 V 11-7  300 5 605 at 23 V 11-8  280 2.9 590 at 21 V11-9  1000 3.5 592 at 20 V 11-10 380 2.3 610, 650 at 21 V 11-11 8 0.25624 at 23 V 11-12 800 2.3 610, 650 at 20 V 11-13 360 1.5 590 at 22 V11-14 160 1.2 590 at 24 V 11-15 80 1.1 597 at 21 V 11-16 170 0.8 615 at21 V 11-17 1300 4 600 at 22 V 11-18 540 1.6 622 at 20 V

Example 12

This example illustrates the preparation of additional phenylpyridineligands.

The phenylpyridine compounds 12-a through 12-j, shown in Table 12 below,were prepared as described in Example 1.

TABLE 12 Compound A R₁ R₂ R₃ R₄ R₅ R₆ R₇ R₈ R₉ 12-a C H CH₃ H H F H F HH 12-b C H CH₃ H H H CF₃ H CF₃ H 12-c C H H CH₃ H F H F H H 12-d C H CH₃H H H CF₃ H H H 12-e C H H CH₃ H H CF₃ H CF₃ H 12-f C H H H H H CF₃ H HH 12-g C H H H H F H F H H 12-h C H t-Bu H H H H F H H 12-i C H t-Bu H HH CF₃ H CF₃ H 12-j C H CH₃ H H H H CF₃ H H

The analytical and NMR data are given in Table 13 below.

TABLE 13 B.p./ mm Hg Yield (m.p.) NB Compound (%) ° C. No ¹H NMR ¹⁹F NMR12-a 61.5 70-72/0.03 101394-104 2.39(3H), −102.96 6.99(2H), (1F, m),7.02(1H), −113.18 7.57(1H), (1F, m) 7.99(1H) 8.56(1H) 12-b 39 66-68/0.01101394-115 2.47(3H), −63.23 (s) 7.17(1H), 7.63(1H), 7.91(1H), 8.48(2H),8.60(1H), 9.00(1H) 12-c 76 75-76/0.01 101394-121 2.25(3H), −110.37(54-56) 6.90(2H), (1F, m) 7.55(2H), −113.50 8.50(1H), (1F, m) 8.85(1H),12-d 76 69-70/0.06 101394-129 2.35(3H), −63.03 (s) (44-46) 7.05(1H),7.55(2H), 8.01(1H), 8.18(1H), 8.50(1H) 12-e 84 (83-85) 102960-482.43(3H) −63.18 (s) 7.66(1H), 7.87(1H), 8.47(2H), 8.59(1H) 12-f 7264-65/0.026 99344-13 7.20(1H), −63.05 (s) 7.65(3H), 8.10(1H), 8.17(1H),8.65(1H), 9.43(1H) 12-g 36 62/0.01 101394-93 6.90(1H), −109.70 7.18(2H),(1F, m) 7.68(2H), −113.35 7.95(1H), (1F, m) 8.65(1H), 12-h 4999-101/0.26 102960-117 — — 12-i 58 108-109/0.1 103555-3 1.35(9H) −63.197.34(1H) 7.72(1H) 7.88(1H) 8.44(2H) 8.61(1H) 12-j 46 76-77/01 102960-1432.46(3H) −62.86 (52-54) 7.15(1H) 7.60(1H) 7.73(2H) 8.11(2H) 8.59(1H)

2-(2′,4′-dimethoxyphenyl)-5-trifluoromethylpyridine was prepared viaKumada coupling of 2-chloro-5-trifluoromethylpyridine with2,4-dimethoxyphenylmagnesium bromide in the presence of [(dppb)PdCl₂]catalyst (dppb=1,4-bis(diphenylphosphino)butane).

Example 13

This example illustrates the formation of dichloro-bridged dinuclearbis-cyclometallated Ir complexes.

The Ir complexes were prepared by the reaction between IrCl₃.nH₂O andthe corresponding 2-arylpyridine in aqueous 2-ethoxyethanol. The methodis similar to the literatures procedure for 2-phenylpyridine (Sprouse,S.; King, K. A.; Spellane, P. J.; Watts, R. J., J. Am. Chem. Soc., 1984,106, 6647-53; Garces, F. O.; King, K. A.; Wafts, R. J., Inorg. Chem.,1988, 27, 3464-71.). A mixture of IrCl₃.nH₂O, a 2-arylpyridine (2.2-2.8equivalents per Ir), 2-ethoxyethanol (ca. 30 mL per 1 g of IrCl₃.nH₂O),and water (ca. 5 mL per 30 mL of 2-ethoxyethanol) was vigorously stirredunder reflux (N₂) for 4-10 hours. After cooling to room temperature,conc. HCl (3 mL per 1 g IrCl₃.nH₂O) was added, and the mixture wasstirred for 30 min. The mixture was diluted with water, stirred for 1-2hours, and filtered. The solid product was washed with water, methanol,and dried under vacuum. The yields ranged from 65 to 99%.

Example 14

This example illustrates the formation of Ir complexes of the inventionhaving the Sixth Formula, where L″ is Cl.

Dicyclometalated Arylpyridine Iridium (III) Mononuclear ComplexesContaining Monodentate Tertiary Phosphine, CO, or Isonitrile Ligands.

A mixture of a the dichloro-bridged dinuclear bis-cyclometallated Ircomplex made as in Example 13, a monodentate ligand L′, and1,2-dichloroethane (DCE) or toluene was stirred under reflux (N₂ or COwhen L′ is CO) until all solids dissolved and then for additional 3min-1 h. The products were isolated and purified by evaporation andcrystallization in air. Detailed procedures for selected complexes aregiven below. All complexes were characterized by NMR spectroscopic data(31 p NMR ³¹P-{¹H} NMR). Satisfactory combustion analyses were notobtained due to insufficient thermal stability of the complexes. Bothisomers of compound 9-k, the major isomer with the nitrogens trans andthe minor isomer with the nitrogens cis, were characterized bysingle-crystal X-ray diffraction.

Complex 9-d (Table 9).

A mixture of the dichloro-bridged dinuclear bis-cyclometallated Ircomplex made with phenylpyridine compound 12-f from Example 12 (100 mg);ligand NC-1, which is 2,6-(CH₃)₂C₆H₃NC, (26 mg) as ligand L′ (purchasedfrom the Fluka line of chemicals, from Sigma-Aldrich); and DCE (1.5 mL)was stirred under reflux for 5 min. Upon cooling to room temperature thestrongly bluish-green photoluminescent solution was treated with hexanes(15 mL, portionwise). The yellow crystals were separated, washed withhexanes (3×3 mL), and dried under vacuum. Yield: 0.115 g (96%). ¹H NMR(CD₂Cl₂, 20° C.), δ: 2.2 (s, 6H, CH₃); 6.35 (d, 1H, arom H); 6.65 (d,1H, arom H); 7.1 (m, 4H, arom H); 7.3 (m, 1H, arom H); 7.5 (m, 1H, aromH); 7.9 (d, 2H, arom H); 8.1 (m, 5H, arom H); 9.4 (d, 1H, arom H); 10.0(d, 1H, arom H). ¹⁹F NMR (CD₂Cl₂, 20° C.), δ: −62.7 (s, 3F, CF₃); −62.8(s, 3F, CF₃).

Complex 9-q (Table 9):

A mixture of the dichloro-bridged dinuclear bis-cyclometallated Ircomplex made with phenylpyridine compound 2-y from Example 1 (120 mg),ligand NC-1, which is 2,6-(CH₃)₂C₆H₃NC, (26 mg) as ligand L′ (purchasedfrom the Fluka line of chemicals, from Sigma-Aldrich); and DCE (2 mL)was stirred under reflux for 10 min. Upon cooling to room temperaturethe strongly bluish-green photoluminescent solution was treated withhexanes (4 mL, portionwise). The yellow crystals were separated, washedwith hexanes (3×3 mL), and dried under vacuum. Yield: 0.13 g (93%). ¹HNMR (CD₂Cl₂, 20° C.), δ: 2.2 (s, 6H, CH₃); 6.35 (d, 1H, arom H); 6.65(d, 1H, arom H); 7.1 (m, 5H, arom H); 8.0 (d, 2H, arom H); 8.25 (m, 4H,arom H); 9.6 (s, 1H, arom H); 10.4 (s, 1H, arom H). ¹⁹F NMR (CD₂Cl2, 20°C.), δ: −62.8 (s, 6F, CF₃); −62.9 (s, 3F, CF₃); −63.0 (s, 3F, CF₃).

Complex 9-j (Table 9)

A mixture of the dichloro-bridged dinuclear bis-cyclometallated Ircomplex made with phenylpyridine compound 2-k from Example 1 (300 mg),triphenylphosphine (120 mg) as ligand L′; and toluene (6 mL) was stirredunder reflux for 10 min. Upon cooling to room temperature yellowcrystals precipitated from the green photoluminescent solution. After 2days at room temperature, hexanes (8 mL) was added. After 1 day, theyellow crystals were separated, washed with hexanes (3×3 mL), and driedunder vacuum. Yield: 0.41 g (97%). ¹H NMR (CD₂Cl₂, 20° C.), δ: 5.5 (m,2H, arom H); 6.7 (m, 2H, arom H); 7.2-7.9 (m, 21H, arom H); 8.05 (s, 2H,arom H); 9.15 (s, 1H, arom H); 9.65 (s, 1H, arom H). ¹⁹F NMR (CD₂Cl₂,20° C.), δ: −62.9 (s, 3F, CF₃); −63.0 (s, 3F, CF₃); −107.9 (m, 1F, aromF); −108.3 (m, 1F, arom F). 31p NMR (CD₂Cl₂, 20° C.), δ: −3.2 (d,J_(P-F)=5.9 Hz). The product contains a minor isomer (ca. 10%) with thefollowing NMR parameters: ¹⁹F NMR (CD₂Cl₂, 20° C.), δ: −63.5 (s, 3F,CF₃); −63.9 (s, 3F, CF₃); −107.4 (m, 1F, arom F); −108.9 (m, 1F, aromF). 31p NMR (CD₂Cl₂, 20° C.), δ: −10.8 (d, J_(P-F)=6.3 Hz).

Complex 9-k (Table 9)

A mixture of the dichloro-bridged dinuclear bis-cyclometallated Ircomplex made with phenylpyridine compound 2-k from Example 1 (102 mg);the triarylphosphine compound (Ar_(f))₃P, where Ar_(f)=3,5-(CF₃)₂C₆H₃(102 mg) as ligand L′; and toluene (8 mL) was stirred under reflux for10 min until all solids dissolved. After cooling to room temperature themixture was treated with hexanes (10 mL), and kept at ca. +10° C. for 3h. The yellow crystalline solid was separated, washed with hexanes, anddried under vacuum. The compound exhibited sky-blue photoluminescence.¹⁹F NMR analysis of this product indicated ca. 10% of unreacted dichlorobridged complex. After heating the solid in boiling toluene in thepresence of L₅ (30 mg) and then cooling at ca. +10° C. for 12 hours,complex 9-k was isolated, free of any dichloro gridged complex. It waswashed with hexanes, and dried under vacuum. Yield: 0.17 g (86%). ¹H NMR(CD₂Cl₂, 20° C.), δ: 5.4 (m, 1H, arom H); 5.9 (m, 1H, arom H); 6.75 (m,2H, arom H); 7.2 (m, 2H, arom H); 7.75 (m, 2H, arom H); 7.9 (m, 7H; aromH); 8.05 (s, 2H, arom H); 8.15 (s, 2H, arom H); 8.85 (s, 1H, arom H);9.4 (s, 1H, arom H). ¹⁹F NMR (CD₂Cl₂, 20° C.), δ: −63.2 (s, 3F, CF₃);−63.9 (s, 3F, CF₃); −64.0 (s, 18F, L₅ CF₃); −105.4 (m, 1F, arom F);−106.1 (m, 1F, arom F). 31p NMR (CD₂Cl₂, 20° C.), δ: −2.2 (d,J_(P-F)=5.9 Hz). This complex has the nitrogen atoms trans to each other(X-ray). In the crop of single crystals submitted for X-ray analysis afew crystals of different shape were also found. One of those few wasalso analyzed by X-ray diffraction, which established cis-arrangement ofthe N atoms around Ir for the minor isomer.

Complex 9-l (Table 9)

Carbon monoxide, as L′, was bubbled through a boiling solution of thedichloro-bridged dinuclear bis-cyclometallated Ir complex made withphenylpyridine compound 2-k from Example 1 (180 mg) in DCE (8 mL). Theheater was turned off and the solution was allowed to cool slowly toroom temperature with CO bubbling through the mixture. When pale-yellowcrystals began to precipitate hexanes (10 mL) was added slowly, in 2-mLportions. After 30 min at room temperature the crystals (whitish-bluephotoluminescent) were separated, washed with hexanes, and dried undervacuum for 15 min. Yield: 0.145 g (78%). ¹H NMR (CD₂Cl₂, 20° C.), δ: 5.6(m, 1H, arom H); 6.15 (m, 1H, arom H); 6.8 (m, 2H, arom H); 7.8 (m, 2H,arom H); 8.1 (m, 2H, arom H); 8.25 (m, 2H, arom H); 9.2 (s, 1H, arom H);10.15 (s, 1H, arom H). ¹⁹F NMR (CD₂Cl₂, 20° C.), δ: −62.8 (s, 3F, CF₃);−62.9 (s, 3F, CF₃); −106.5 (m, 1F, arom F); −106.7 (m, 1F, arom F).

Complexes 9-a, 9-b, 9-c, 9-e, 9-f, 9-h, and 9-i, were made using thesame procedure as for complex 9-d, using phenylpyridine compounds 12-a,12-c, 12-g, 12-d, 2-k, 12-f, and 2-k, respectively.

Example 15

Thin film OLED devices were fabricated using the procedure according toExample 7. A summary of the device layers and thicknesses is given inTable 14. In all cases the anode was ITO as discussed above, and thecathode was Al having a thickness in the range of 700-760 Å.

TABLE 14 MPMP = bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylphenyl)methane DPA = 4,7-diphenyl-1,10-phenanthroline HT layer EL layer ETlayer Sample (Thickness, Å) (Thickness, Å) (Thickness, Å) 15-1 MPMPCompound 9-a DPA (516) (408) (413) 15-2 MPMP Compound 9-c DPA (518)(404) (402) 15-3 MPMP Compound 9-d DPA (508) (354) (421) 15-4 MPMPCompound 9-e DPA (504) (403) (410) 15-5 MPMP Compound 9-f DPA 102924-5(501) (407) (415) 15-6 MPMP Compound 9-g DPA 102924-40 (518) (404) (405)

The OLED samples were characterized as in Example 7, and the results aregiven in Table 15 below.

TABLE 15 Electroluminescent Properties of Iridium Compounds Peak PeakApproximate Peak Radiance, efficiency, Wavelengths, Sample Cd/m2 Cd/A nm15-1 6 0.7 450 + 500 at 16 V 15-2 1 0.25 510 at 21 V 15-3 60 0.8 464 +493 at 22 V 15-4 25 1.2 460 + 512 at 23 V 15-5 320 2.4 538 at 22 V 15-6350 1.5 484 + 509 at 23 V

What is claimed is:
 1. A compound having the following formula:


2. A compound having the following formula:


3. A compound having the following formula:


4. A compound having the following formula:


5. A compound having the following formula:


6. A compound having the following formula:


7. A compound having the following formula:


8. A compound having the following formula:


9. A compound having the following formula:


10. A compound having the following formula:


11. An electronic device comprising an organic layer comprising acompound having the formula selected from the formulas as set forth inclaims 1-10.